Stair-climbing stroller

Abstract

The stair-climbing stroller is a baby stroller with retractable front and rear wheels for use on flat travel surfaces and a pair of tracks for use on inclined travel surfaces including, but not limited to, staircases. The front wheels are coupled to a pivoting front wheel support shaft and the rear wheels are coupled to a pivoting rear wheel support shaft. A wheel retract motor located on the underside of the stroller may cause a retraction drive shaft to pivot the front and rear wheel support shafts, retracting the wheels. When the front and rear wheels retract, the stroller may be lowered such that the left and right track rest on the ground. Left and right track motors may then be used to drive the stroller up an inclined travel surface using the tracks.

What is claimed is: 
     
       1. A stair-climbing stroller comprising:
 a stroller body, two front wheels, two rear wheels, a front wheel support shaft, a rear wheel support shaft, a front gear assembly, a rear gear assembly, a retraction drive shaft, a wheel retract motor, a left track drive motor, a right track drive motor, one or more batteries, a left track, and a right track; 
 wherein the stair-climbing stroller is adapted to be a conveyance for an infant or toddler; 
 wherein the stair-climbing stroller rides on the two front wheels and the two rear wheels to move over a flat travel surface; 
 wherein the stair-climbing stroller rides on the left track and the right track to ascend or descend an inclined travel surface, including, but not limited to, a staircase; 
 wherein the two front wheels and the two rear wheels retract so that the left track and the right track contact the inclined travel surface; 
 wherein when in an extended mode, the two front wheels and the two rear wheels extend vertically downward from the front wheel support shaft and the rear wheel support shaft, respectively; 
 wherein when in the extended mode, the distance between the front wheel support shaft and the bottom of the two front wheels matches the distance between the rear wheel support shaft and the bottom of the two rear wheels; 
 wherein when in the extended mode, the two front wheels and the two rear wheels lift the stroller body to a height such that the left track and the right track do not contact the flat travel surface; 
 wherein when in a retracted mode, the front wheel support shaft turns in a direction that pivots the two front wheels up and to the rear; 
 wherein when in the retracted mode, the rear wheel support shaft turns in a direction that pivots the two rear wheels up and to the front; 
 wherein as the two front wheels and the two rear wheels pivot they lower the stroller body such that the left track and the right track contact the flat travel surface; 
 wherein the two front wheels and the two rear wheels continue to pivot until they are pointed at each other and at a height such that they do not contact the flat travel surface. 
 
     
     
       2. The stair-climbing stroller according to  claim 1 
 wherein the stroller body is adapted to be an enclosure surrounding the infant or toddler; 
 wherein the stroller body is open at the top to provide access to a passenger compartment located within the stroller body; 
 wherein the passenger compartment is a seat, a mattress, or padding adapted for the infant or toddler to sit or recline upon; 
 wherein the stroller body conceals hardware located beneath the passenger compartment. 
 
     
     
       3. The stair-climbing stroller according to  claim 2 
 wherein the stroller body comprises a canopy; 
 wherein the canopy is a transparent cover over the top of the stroller body; 
 wherein the canopy is adapted to provide protection for the infant or toddler from the sun, wind, and insects; 
 wherein the canopy comprises one or more air vents to allow circulation of fresh air within the passenger compartment; 
 wherein the canopy is hingedly coupled to the top of the stroller body; 
 wherein the stroller body comprises a telescopic handle; 
 wherein the telescopic handle is coupled to the rear of the stroller body and extends up to a height above the stroller body; 
 wherein the telescopic handle is used to push and steer the stroller body. 
 
     
     
       4. The stair-climbing stroller according to  claim 3 
 wherein the telescopic handle comprises an operator control panel; 
 wherein the operator control panel provides a plurality of operator controls that control operation of the stroller body; 
 wherein the plurality of operator controls cause retraction or extension of the two front wheels and the two rear wheels; 
 wherein the plurality of operator controls cause the left track to turn in a direction to cause forward motion, to turn in a direction to cause rearward motion, or to stop; 
 wherein the plurality of operator controls cause the right track to turn in a direction to cause forward motion, to turn in a direction to cause rearward motion, or to stop. 
 
     
     
       5. The stair-climbing stroller according to  claim 4 
 wherein the operator control panel comprises an on-off control, a power indicator, a battery state indicator, or combinations thereof. 
 
     
     
       6. The stair-climbing stroller according to  claim 4 
 wherein the two front wheels are swivel wheels or casters that are pivotably mounted to the front wheel support shaft; 
 wherein the two rear wheels are swivel wheels or casters that are pivotably mounted to the rear wheel support shaft. 
 
     
     
       7. The stair-climbing stroller according to  claim 6 
 wherein the two front wheels swivel to change directions while the two rear wheels are fixed to travel in a straight line. 
 
     
     
       8. The stair-climbing stroller according to  claim 7 
 wherein the front gear assembly redirects rotation of the retraction drive shaft by 90 degrees at the front of the retraction drive shaft; 
 wherein the front gear assembly transfers rotational energy of the retraction drive shaft to the front wheel support shaft; 
 wherein the rear gear assembly redirects rotation of the retraction drive shaft by 90 degrees the rear of the retraction drive shaft; 
 wherein the rear gear assembly transfers rotational energy of the retraction drive shaft to the rear wheel support shaft; 
 wherein the front gear assembly and the rear gear assembly comprise one or more worm gears or one or more bevel gears; 
 wherein the retraction drive shaft runs horizontally from the front of the stroller body to the rear of the stroller body; 
 wherein the retraction drive shaft is supported at each end by a bearing. 
 
     
     
       9. The stair-climbing stroller according to  claim 8 
 wherein the wheel retract motor converts electrical energy into mechanical energy; 
 wherein the wheel retract motor causes rotation of the retraction drive shaft when electrical energy is applied to the wheel retract motor; 
 wherein the electrical energy applied to the wheel retract motor is controlled by the operator control panel; 
 wherein the wheel retract motor is mounted to the bottom center of the stroller body; 
 wherein the wheel retract motor is coupled either directly or indirectly to the retraction drive shaft. 
 
     
     
       10. The stair-climbing stroller according to  claim 9 
 wherein when the wheel retract motor is energized to turn in a first direction, rotation of the retraction drive shaft is transferred to the front wheel support shaft and to the rear wheel support shaft such that the two front wheels and the two rear wheels retract; 
 wherein when the wheel retract motor is energized to turn in a second direction, rotation of the retraction drive shaft is transferred to the front wheel support shaft and to the rear wheel support shaft such that the two front wheels and the two rear wheels extend; 
 wherein a hand crank is coupled to the retraction drive shaft at the rear of the stroller body to manually retract or extend the two front wheels and the two rear wheels. 
 
     
     
       11. The stair-climbing stroller according to  claim 10 
 wherein the left track drive motor converts electrical energy into mechanical energy; 
 wherein the left track drive motor causes rotation of the left track when electrical energy is applied to the left track drive motor; 
 wherein the electrical energy applied to the left track drive motor is controlled by the operator control panel; 
 wherein the right track drive motor converts electrical energy into mechanical energy; 
 wherein the right track drive motor causes rotation of the right track when electrical energy is applied to the right track drive motor; 
 wherein the electrical energy applied to the right track drive motor is controlled by the operator control panel. 
 
     
     
       12. The stair-climbing stroller according to  claim 11 
 wherein the one or more batteries comprise one or more energy-storage devices; 
 wherein the one or more batteries are a source of electrical energy to operate the left track drive motor, the right track drive motor, and the wheel retract motor; 
 wherein the one or more batteries are replaceable or rechargeable. 
 
     
     
       13. The stair-climbing stroller according to  claim 12 
 wherein the left track is located on the lower, left side of the stroller body; 
 wherein the right track is located on the lower, right side of the stroller body; 
 wherein when the two front wheels and the two rear wheels are in the retracted mode, the left track and the right track contact the flat travel surface and support the weight of the stair-climbing stroller. 
 
     
     
       14. The stair-climbing stroller according to  claim 13 
 wherein the left track and the right track are mirror-images of each other relative to a vertical, longitudinal center plane running through the stair-climbing stroller. 
 
     
     
       15. The stair-climbing stroller according to  claim 14 
 wherein a track comprises a track belt, a drive sprocket, an idler, and a plurality of roller sprockets; 
 wherein the track is the left track or the right track; 
 wherein the track belt is a continuous and endless loop of synthetic rubber; 
 wherein the track belt forms a travel surface for the drive sprocket, the idler, and the plurality of roller sprockets to move over; 
 wherein as the stair-climbing stroller moves forward, the rear edge of the track belt is pulled up and moves forward to the front of the track where it descends in front of the track to be used again. 
 
     
     
       16. The stair-climbing stroller according to  claim 15 
 wherein the track belt comprises toothed ridges oriented laterally on the interior of the track belt; 
 wherein the track belt comprises ridges or other contours on the exterior surface of the track belt to increase friction between the track belt and the inclined travel surface. 
 
     
     
       17. The stair-climbing stroller according to  claim 16 
 wherein the drive sprocket is a wheel that is driven, directly or indirectly, by a track motor; 
 wherein the track belt is forced to move by rotation of the drive sprocket; 
 wherein the drive sprocket comprises a series of lateral grooves that engage with the toothed ridges on the track belt; 
 wherein the track motor is the left track drive motor or the right track drive motor. 
 
     
     
       18. The stair-climbing stroller according to  claim 17 
 wherein the idler is a wheel that guides the track belt at the opposite end of the track belt from the drive sprocket; 
 wherein the plurality of roller sprockets are wheels that guide and support the track belt between the drive sprocket and the idler; 
 wherein the drive sprocket, the plurality of roller sprockets, and the idler are pivotably coupled to the stroller body in an evenly spaced, linear formation from front to rear. 
 
     
     
       19. The stair-climbing stroller according to  claim 18  wherein the idler is spring-loaded and keeps the track belt under tension.